Valve for rock drills



Jan. 17, 1928. 1,656,541

W. A. SMITH VALVE FOR ROCK DRILLS Filed Nov. 20. 1926 INVENTOR.

117' Ram JI- milk BY V Hm ATTOR EY.

Patented Jan. 17, 1928.

UNITED assen PATENT OF ICE- WILLIAM A. summer Sims, PENNSYLVANIA, Assrenon, T rnennsonn-aann COMPANY, OF JERSEY CITY, NEW JERSEY, A coaroaarron on NEW JERSEY,

vanvn son noon nniLLs.

Application filed November 20, 1926. Serial NO. 149,576. A

This invention relates to rock drills, but more particularly to a spool type distributing valve for fluid actuated rock drills of the hammer type.

An object of the invention is to obtain a substantial reduction of the pressure fluid admitted to one end of the valve chamber for throwing the valve in one direction preparatory to the admission of pressure-fluid to the opposite end of the valve chamber for reversing the valve,

Other objects will appear hereinafter.

The invention consists of the combination of elements and features of construction substantially as hereinafter described and claimed and illustrated in the accompanying drawings, in which Figure 1 is a diagrammatical sectional elevation eta portion of a rock drillshowing the valve in position to admit pressure fluid to one end of the cylinder, and

Figure 2 is a view similar toFigure 1 showing the valve in position to admit pressure fluid to the other end of the cylinder. Referring to the drawings, A designates a cylinder having a chamber Bin which is disposed a reciprocatory hammer piston C. The piston C has a plain reduced forward extension I) slidable in a bore in the front end of the cylinder A to deliver blows of impactto a drill steel E supported in this instance by the front end of the cylinder.

Disposed on the cylinder A and preferably integral therewith is a valve chest F having a valve chamber G. The valve chamber G in this instance is of uniform diameter throughout its length and extends through the valve chest. Plugs H form closures for the ends of the valve chamber G and have reduced portions J which extend into the chamber G.

The admission of pressure fluid into the chamber G is eilected through a connection K communicating with a central port L in i the chamber G through a passage 0. Pressure fluid is conveyed to the ends'ot the cyl inder A through supply passages P and Q leading from points forwardly and rear- Wardly respectively of the central port L to the front and rearward ends of the cylinder A.

Disposed within the chamber is a distributing valve R. The valve R is in many respects like that disclosed in United States Patent No. 1,589,255 entitled Rock drill spool valve, granted Junel5, 1926, to W. A. Sm1th, and, accordinglyhasa centralhead- S and end heads T and U for controlling the admission of pressure fluid from the chamber G through the supply passages P and Q to the ends of the cylinder.

In the present'ins'ta-nce the end heads T and Ualso control one end of the valve controlling passages V and W leading from points near the ends of the valve chamber G to points on opposite sides of the center of the cylinder A. The controlling passages V and W are preferably crossed so that the front passage V communicates with the rearward port-ion of the cylinder A and the rearward passage W communicates with the front portion of the cylinder A. The. admission of pressure fluid into the controllmg passages V and W is controlled by the piston C. Front and rearward exhaust ports X and Y are formed in the valve chest F and are controlled by the end heads T and U respectively.

As in the valve disclosed in the aforementioned patent, the present valve also is provided with ports Z and b in the end heads T i and U to register with the controlling passages V and V for admitting pressure fluid trom the cylinder A to the ends of the valve chamber G for actuating the valveand for exhausting pressure fluid from the ends of the chamber after the valve again approaches its initial position. Additional means are provided, however, for insuring a suitable reduction in pressure of the fluid utilized for throwing the valve so that the pressure fluid admitted to the one end of the valve chamber G may more readily overcome the pressure previously admitted to the other end of the chamber. To this end leak ports 0 and a? are formed in the heads T and IT respectively, preferably between the ends of the valve and the ports Z and b.

The ports a and (Z are so positioned that when the valve is in its limiting positions, the leak port in that end of the valve to which pressure fluid has been admitted for actuating it will register with the valve controlling passage leading from that end.

In the operation of the device with the valve and piston in the positions illustrated in Figure 1, pressure fluid in the central port L will flow through the chamber G between the heads S and U, thence through the rearward supply passage Q to the rear- 

